Method of performing an area update for a terminal equipment in a communication network

ABSTRACT

The present invention proposes a method of performing an area update for a terminal equipment ( 4 A,  4 B) in a communication network ( 1, 2, 3, 5, 6 ), the communication network comprising at least two areas ( 5, 6 ) being defined within an access network, at least one of said areas being served by at least two core network elements ( 1 - 2, 2 - 3 ) of corresponding network element types, each of said at least two core network elements communicating with said access network defining said areas via a different interface (Iu, Gb), the method comprising the steps of: monitoring, at the terminal equipment side, via which of said at least two core network elements ( 1, 2 ) serving a currently visited area ( 5 ) the communication with the terminal equipment ( 4 A) is effected, detecting, at the terminal equipment side, an area update condition for said terminal ( 4 A,  4 B), requesting, by said terminal equipment, an area update for said terminal equipment ( 4 B), and wherein said terminal equipment ( 4 B) sets an identifier in said area update request identifying the core network element via which the communication with the terminal equipment ( 4 A) has previously been effected. Still further, the present invention proposes also an accordingly adapted terminal equipment.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 10/433,104, filed on Sep. 5, 2003, and issued as U.S. Pat. No.7,069,022 on Jun. 27, 2006, which is a 371 of and claims priority toPCT/EP00/12101, filed on Dec. 1, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to method of performing an area update fora terminal equipment in a communication network, and also to acorrespondingly adapted terminal equipment.

2. Description of the Prior Art

Generally, communication networks consist of an access network and acore network. The access network is specifically adapted to a connectiontechnology used for terminal equipment communicating with/via thenetwork, whereas the core network is connection technology independentand manages the functions the network offers to the terminals registeredin the network.

Currently, for example, there exists the GSM network (GSM=GlobalStandard for Mobile Communication), consisting of a so called basestation subsystem BSS as the access network part and the core networkcomprising e.g. the mobile services switching center MSC, a homelocation register HLR, visitor location register VLR etc. The basestation subsystem BSS is connected to the core network via an interfaceknown as A-interface. Further, the base station subsystem comprises aplurality of base station BS and/or base transceiver stations BTS undercontrol of a base station controller BSC. Each base station BS defines acell and a plurality of cells form a location area. Typically, alocation area has a size (number of cells) such that one MSC may effectcontrol of communication within a location area. The above brieflydescribed GSM communication system is also known as a second generationsystem (2G), which initially was basically intended and provisioned forspeech data transmission (circuit switched data, real time datatransmission).

Meanwhile, however, the need for packet data transmission (datadifferent from speech) (non-real time, packet switched data) hasincreased, which led to the development of a so-called GPRS network(General Packet Radio Service). The GSM and GPRS communication networkexist somewhat in parallel and rely on substantially the same accessnetwork. With regard to the core network, in a GPRS network the functionof the MSC is performed by so-called GPRS Support Nodes GSN, among whichthere are Serving GPRS support nodes SGSN (and gateway GPRS supportnodes GGSN). The BSS is connected to the SGSN via an interface known asGb interface.

Hence, a single cell in such a communication network scenario may beconnected to different core network elements of different types, i.e.SGSN and/or MSC/VLR.

Now, in case a terminal equipment (for example, mobile station MS) hasmoved within the network such that a new MSC/VLR and/or new SGSN is incharge for controlling communication in that part of the network, thenecessity for a routing and/or location area update arises. The terminalthen performs a routing and/or location area update, that is requests anew SGSN and/or MSC/VLR to take over communication control for therequesting terminal equipment. In such a routing and/or location areaupdate RAU/LAU, the terminal equipment transmits the old, that isprevious, routing area identity RAI and/or location area identity LAI ofthe routing/location area it was previous attached to and/orcommunicating with.

Using the transmitted RAI (LAI), the new core network element finds anaddress of the core network element previously in charge forcontrolling/managing communication with the terminal, that is the newcore network element in the new routing area may locate the previous(old) core network element (SGSN and/or MSC/VLR) from where thesubscriber data for the requesting terminal equipment are sent to thecore network element at the new (current) location (new SGSN and/or newMSC/VLR).

With a continuously progressing development in communication networks,also a so-called third generation (3GPP=3^(rd) generation partnershipproject) of communication networks is being developed. The communicationnetwork of the third generation is also referred to as UMTS (UniversalMobile Telecommunication System). According to UMTS/3GPP specifications,base stations in GSM correspond to Node_B's, mobile stations MS asterminal equipment are referred to as user equipment UE, etc. Also witha third generation (3G) communication network, a circuit switched datatransfer (for example, for speech) as well as a packet switched datatransfer is enabled. To this end, the 3G access network is connected orat least connectable via a Iu-CS interface to a 3G MSC/VLR and via aIu-PS interface to a 3G SGSN.

With a demand that most recently developed equipment should be downwardcompatible, that is compatible to previously developed standardizedsystems, there will arise a situation, in which, for example, a 2G SGSNas well as a 3G SGSN are both connected to the same cell and/or location(routing) area of an access network.

For example, so-called GERAN cells enable the connection of 2G as wellas of 3G core network elements (for example, 2G SGSN and 3G SGSN) to thesame cell/location (routing) area. (GERAN=GSM EDGE Radio Access Network,EDGE=Enhanced Data rates for GSM Evolution). In case of SGSN's as anexample for core network elements, a 2G SGSN is connected to a GERANcell/routing area (that is to the GERAN access network) via the Gbinterface, whereas a 3G SGSN is connected thereto via the Iu-PSinterface. Such a connection to a single GERAN cell/routing area ofdifferent core network elements of the same type (that is SGSN withIu-PS or Gb interface), is, however, required in 3G communicationnetworks.

However, because a single routing area (or cell (as a smallestconceivable routing area)) can be connected to two different SGSN's, onewith Iu and other with Gb interface, the new SGSN receiving the terminalequipment's routing area update (RAU) request upon the detection of anecessity for routing area update does not know from which SGSN itshould request the subscriber information associated with the requestingterminal, because the old routing area identifier RAI identifying therouting area in which the terminal equipment was previously present mayindicate two different core network elements (i.e. 2G SGSN and 3G SGSN).

If, however, in the chosen example, a new SGSN does not know whichprevious SGSN to contact to retrieve the subscriber information of therequesting terminal equipment, a routing area update for a terminalequipment may fail and a call may be dropped.

Previously, in order to solve such a problem, it has been proposed toassign two separate routing area identities (RAI) to each routing area(and/or cell). However, assigning two identities inevitably doubles theaddress space for the routing areas, which is undesirable in terms of anadditional need of network management in the core and access network.Also, the respective access network RAN (more specifically, the basestations and/or Node_B's) will have to broadcast two routing areaidentities for each routing area, while also terminals listening to thebroadcasted information will have to be adapted to properly processand/or interpret the two broadcasted identities per routing area.

Thus, this previously proposed solution requires multiple changes to theexisting communication network.

Document WO-A-00/21319 discloses the identification of a mobile stationin a packet radio network. In this connection, the prior art documentdiscloses that a temporary identity allocated to a mobile station by acore network element is allocated such that the network element encodesits own identifier, or part of it, into the temporary identity. Theidentity of the network element such as a SGSN node is assumed in thisprior art to be derivable on the basis of the identities of the routingarea served by the network element. However, as explained above, thisassumption is no longer valid as a respective routing area is handled byseveral (different) network elements of the same network element typebut of different core network types.

Therefore, the teaching as presented in WO-A-00/21319 can not betransferred to the present scenario in which it is required that arespective routing area has to be connectable to different core networkelements of the same type.

SUMMARY OF THE INVENTION

Hence, the present invention provides an improved method of performing arouting area update for a terminal equipment in a communication network,which is suitable for a scenario in which it is required that arespective routing area has to be connectable to different core networkelements of the same type, while still keeping the amount of resultingchanges small.

The present invention provides a method of performing an area update fora terminal equipment in a communication network, the communicationnetwork comprising at least two areas being defined within an accessnetwork, at least one of said areas being served by at least two corenetwork elements of corresponding network element types, each of said atleast two core network elements communicating with said access networkdefining said areas via a different interface, the method comprising thesteps of: monitoring, at the terminal equipment side, via which of saidat least two core network elements serving a currently visited area thecommunication with the terminal equipment is effected, detecting, at theterminal equipment side, an area update condition for said terminal,requesting, by said terminal equipment, an area update for said terminalequipment, and wherein said terminal equipment sets an identifier insaid area update request identifying the core network element via whichthe communication with the terminal equipment has previously beeneffected.

According to further developments of the present invention,

-   -   said identifier set by said terminal equipment is part of the        routing area identifier RAI;    -   said routing area identifier RAI is composed of a mobile country        code MCC, a mobile network code MNC, a location area code LAC,        and a routing area code RAC;    -   said identifier is at least one predetermined bit within said        routing area identifier;    -   said identifier is the most significant bit of said routing area        code RAC;    -   said identifier is the most significant bit of said location        area code LAC;    -   a setting state of said most significant bit indicates a        respective interface via which the previous routing and/or        location area update has been performed such that said access        network is connected to one of said different core networks;    -   for 2^(N) core network elements of a same network element type,        the number of predetermined bits is predetermined to be N,    -   said identifier set by said terminal equipment is part of the        location area identifier (LAI).

Stated in other words, the core network element via which thecommunication with the terminal equipment has previously been effectedis identified with the aid of the type of access network interfacebetween the access network and the core network element.

Also, the present invention is for example achieved by a terminalequipment adapted to communicate via an access network with differentcore networks and adapted to carry out the method as defined hereinabove.

Accordingly, with the present invention it is advantageously enabledthat the above mentioned problem is solved.

Also, no changes to the radio access network are required and there-allocation of the routing area identifier, more precisely, there-allocation of the routing area code within the routing areaidentifier, does not require any procedural changes to existingsignaling. Re-allocation of the routing area identifier here means thatonly part (some bits) of the routing area identifier is used for routingarea identification while another part of it is used for identificationof the core network type to which the access network is connected forcommunication with the terminal equipment. Stated in other words, theRAI is partitioned to be used in parallel for routing area and corenetwork identification.

Furthermore, as the identifier is carried as a part of the RAI thisenables that no modifications are required to previously existing(“old”) core network elements.

Rather, it is merely required to adapt the mapping involved with therouting area code RAC.

Still further, due to the terminal equipment performing the setting ofthe identifier, the core network is at least relieved from this networkmanagement function to be performed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and still other objects, features and advantages of thepresent invention will become more fully apparent upon consideration ofthe accompanying drawings, in which:

FIG. 1 illustrates a basic scenario of routing areas each connected totwo core network elements of a same type but of respective differentcore networks, and a routing area update signaling involved in routingarea update.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will now be explained in detail with reference tothe drawings.

FIG. 1 illustrates a basic scenario of routing areas each connected totwo core network elements of a same type but of respective differentcore networks, and a routing area update signaling involved in routingarea update.

Nevertheless, it has to be noted that the cells of the new routing areado not necessarily have to be connected to two core network elements ofa same type but of respective different core networks, rather it issufficient for the present invention if at least one, that is only thepreviously visited, routing area to which registration has beenperformed is connected to two core network elements of a same type butof respective different core networks.

Firstly, the basic scenario will statically be described, that iswithout a focus to any signaling messages exchanged between the networkelements.

FIG. 1 illustrates two routing areas 5 and 6, respectively. However,more than two routing areas are normally present within a communicationnetwork, but in order to keep the illustration simple for explanatorypurposes, only two are shown. Each routing area 5, 6 is roughlyrepresented as consisting of several individual cells. A cell isintended to be represented by a respective antenna representation as asymbol for a base station (not shown) with corresponding coverage area.Each routing area is identified by a routing area identifier RAI.

The routing area identifier RAI consists of four individual fields, i.e.MCC (mobile country code), MNC (mobile network code), LAC (location areacode), and RAC (routing area code). The MCC identifies the country inwhich the network is operated, the MNC identifies the network (and viathe network, the operator thereof). The LAC identifies the location are(i.e. cell or cell group). MCC, MNC, and LAC, however, of routing areas5 and 6, respectively, are not shown in the FIG. 1. Rather, FIG. 1indicates only the value of the routing area code RAC for these routingareas (RAC1 and RAC2). The RAC is an octet of eight bit length, and itsvalue is indicated in hexadecimal notation. Namely, RAC1=70 “H”=01110000 “B” in binary representation. Likewise, routing area 6 isidentified by routing area code RAC2=71 “H”=0111 0001 “B”.

Each routing area 5, 6 represents an access network of a type, to whichat least two types of core networks are connectable. For the presentinvention, a GERAN cell/routing area has been chosen as an example.However, the present invention is not limited to GERAN.

Thus, to the routing area 5 there is connected

-   1) a 2G core network for packetized data transmission represented by    a core network element of a type of a 2G SGSN denoted by numeral 2,    connected via an interface Gb, and-   2) a 3G core network for packetized data transmission represented by    a core network element 3G SGSN denoted by numeral 1, connected via    an interface Iu-PS (Iu interface for packet switched traffic).

Likewise, to the routing area 6 there is connected

-   1) a 2G core network for packetized data transmission represented by    a core network element of a type of a 2G SGSN denoted by numeral 2    (the identity of the 2G core network elements is for simplification    of the explanation and drawing only, it is of course possible that    different core network elements of the same functionality of the 2G    core network are connected to different routing areas without any    change in the present invention), connected via an interface Gb,-   and 2) a 3G core network for packetized data transmission    represented by a core network element 3G SGSN denoted by numeral 3,    connected via an interface Iu-PS (Iu interface for packet switched    traffic).

As already mentioned before, it is also possible that the routing area 6(to which the terminal equipment moves from the old/previous routingarea) is connected only to a single core network element, while thepresent invention would still remain applicable to such a scenario.

A terminal equipment such as a mobile station MS or user equipment UEdenoted by reference sign 4A, 4B representative of respective differentsituations for the terminal is communicating via/with the network andits network elements. Any terminal equipment may be used (radio ornon-radio) as long as it is adapted for communication with differentcore networks. Also, any access network may be used, that is radioaccess network or non-radio access network, as long as it is adapted tothe used terminal equipment.

The terminal equipment, in a first situation, is denoted by 4A and isattached to the “left hand” routing area identified by RAC1=“70 Hex”.The terminal equipment has a knowledge of the routing area identifier asthe identifier is broadcasted by the access network such as GERAN.Namely, at the terminal equipment side, it is monitored via which ofsaid at least two core network elements serving the currently visitedrouting area 5 the communication with the terminal equipment 4A iseffected.

As the terminal in the illustrated example is a mobile terminal, itmoves during communication as indicated by the dotted arrow. The movingof the terminal equipment results in the terminal equipment leaving theprevious routing area 5 and entering a new routing area 6. Thus, uponentering the new routing area the terminal equipment detects thiscondition resulting in the necessity for a routing area update to beperformed.

For explanatory purposes only, it is now assumed that the routing areaupdate request issued by the terminal equipment is forwarded to the corenetwork element denoted by numeral 3 of the 3G core network, that is tothe 3G SGSN connected to the routing area 6.

Based on the result of monitoring, the terminal 4B in this situationknows the type of access network interface (Iu or Gb) between the radionetwork and the core network element via which the communication withthe terminal equipment 4B (in situation 4A) has previously beeneffected. Thus, dependent on the result, the terminal equipment isadapted to forward two different RAU requests to the “new” core networkelement, that is 3G SGSN denoted with 3.

In a first case, it is assumed that in the routing area 5 which haspreviously been left by the terminal equipment, the connection has beenestablished via the Gb interface to the 2G SGSN denoted by 2. In therouting area update request denoted by 7 a, the terminal equipmentincludes the information on the old and/or previous routing area code(unchanged) so that an information of an RAI with an RAC=70 “Hex” isincluded in the request. Based on the information in the mostsignificant bit MSB of the RAC=0111 0000 “B”, i.e. “0”, the core networkelement 3 receiving the routing area update request knows the type ofthe interface via which the (“previous”) communication in the previousrouting area was effected. The interface type is again representative ofthe core network type (e.g. 2^(nd) or 3^(rd) generation). Then, as the3G SGSN denoted with 3 knows that in the previous routing area 5 thecommunication was effected via the interface Gb, it addresses the 2GSGSN core network element denoted by 2 in order to obtain the subscriberinformation associated to the terminal equipment 4A, 4B requesting therouting area update. This exchange of information between the 2G SGSNdenoted by 2 and the 3G SGSN denoted by 3 is indicated by the arrow 7 b.

If, on the other hand, it is assumed that in the routing area 5 whichhas previously been left by the terminal equipment, the connection hasbeen established via the Iu-PS interface to the 3G SGSN denoted by 1,then in the routing area update request denoted by 8 a, the terminalequipment includes the information on the old and/or previous routingarea code with a modified most significant bit so that an information ofan RAI with an RAC=F0 “Hex” is included in the request. Based on theinformation in the most significant bit MSB of the RAC=1111 0000 “B”,i.e. “1”, the core network element 3 receiving the routing area updaterequest knows the type of the interface via which the previouscommunication in the previous routing area was effected. The interfacetype is again representative of the core network type (e.g. 2^(nd) or3^(rd) generation). Then, as the 3G SGSN denoted with 3 knows that inthe previous routing area 5 the communication was effected via theinterface Iu-PS, it addresses the 3G SGSN core network element denotedby 1 in order to obtain the subscriber information associated to theterminal equipment 4A, 4B requesting the routing area update. Thisexchange of information between the 2G SGSN denoted by 2 and the 3G SGSNdenoted by 3 is indicated by the arrow 8 b.

A similar signaling (not shown) takes place in case of the routing areaupdate request being forwarded to the core network element 2 (that is 2GSGSN). If in the previous routing area, communication was effected viathe Gb interface, the 2G SGSN 2 learns that it does not have to contactany other core network element as in the illustrated example it itselfhas been in charge for communication with the terminal equipment. If onthe other hand in the previous routing area, communication was effectedvia the Iu-PS interface, the 2G SGSN 2 learns that it has to contact thecore network element 3G SGSN denoted by 1, so that a correspondingsubscriber data exchange would be effected between 3G SGSN denoted by 1and 2G SGSN denoted by 2.

Thus, each routing area has a single RAI containing a LAC and RAC. Theterminal equipment indicates in the registration to a new core networkelement upon routing area update the mode (that is the type ofinterface, Iu versus Gb) in which a previous registration has beeneffected to a core network element in a previous routing area.

The invention re-allocates the RAC space by shortening the RAC spacefrom eight to seven bits. Then, the most significant bit in the RACindicates the type of the interface via which communication in theprevious routing area was effected.

Also, in a case there is an access network which is simultaneouslyadapted for circuit switched data transmission, in FIG. 1 also aninterface Iu-CS to a 3G MSC/VLR (not shown) and an A-interface to a 2GMSC/VLR (not shown) would be present. In such a case, the mostsignificant bit of the LAC within the RAI is used for indicating thetype of interface via which communication in the previous routing areawas effected. This would result in shortening the LAC from 16 to 15bits. A corresponding signaling in connection with routing area updatewill in this case be similar to the one as explained above.

According to a conceivable modification, also the LAC only could be usedin case of a routing area updating. This alternative has the advantagethat the RAC would not have to be shortened, since it is already only 8bits long that is according to the modification, the most significantbit of LAC in RAI indicates the previous type of interface used. Thisalternative could be applicable if only routing areas can be connectedto two core network nodes, but location areas are always connected toonly one core network node.

Still further, herein above an explanation has been given for cases inwhich there is provided an access network to which two types of corenetworks are connectable. Nevertheless, the present invention remainsstill applicable in a case in which 2^(N) types of core networks (with acorresponding number of 2^(N) core network elements of a same networkelement type) are connectable to the access network (routing area). Insuch a case, the invention is easily to be adapted by selecting N as thenumber of predetermined bits, by which the LAC and/or RAC is to beshortened.

Thus, as has been explained above in connection with the presentinvention, the present invention solves a previously non-existingproblem as only one core network element of a type (for example, SGSN)per routing area RA was possible. The invention resides in using, forexample, the most significant bit of the routing area code RAC of the“old”, i.e. previous routing area RA to indicate to the new networkelement such as a SGSN the type of the old SGSN. Otherwise, the oldrouting area code RAC is carried in the GPRS routing area update messageto the new SGSN normally, that is unchanged. By inspecting the bit inthe routing are identifier RAI and/or routing area code RAC and/orlocation area code LAC, the network element such as the SGSN knows whichand which kind of network element (e.g. SGSN) to contact. In otherwords, in the network elements such as SGSN's, there will be twomappings for a masked routing area code RAC. One for most significantbit value 1 and one for value 0. The mappings correspond to thedifferent core network systems.

It should be noted that although the preceding description referred torouting areas as an example, the present invention is applicable toother types of areas in communication networks such as location areas orsimply cells as a minimal area. In addition, although the descriptionfocused on plural core network elements of same network element typebeing connected to an area (for example, SGSN's), the invention is notlimited thereto. Rather, the invention is also applicable to cases inwhich only plural core network elements of corresponding network elementtypes are connected to an area. This means that the core networkelements merely have to be provided with roughly corresponding functionsto be performed, that is, for example, the core network elementsconnected to an area need only to have a common subset of functions ofthe overall functions which they are adapted to perform. Still further,the above description focused on a case in which the core networkelements were assumed to be belonging to different core networks (secondgeneration 2G and third generation 3G). Nevertheless, this is notrequired for the present invention and the core network elements couldactually be in the same common network (for example, an operator's IPsubnet), as long as the access network interface types via which theseare connected (such as Iu-PS and Gb) are different.

The correspondence of the network element types stated in above can beinterpreted differently in different embodiments. In some embodiments ofthe invention the two core network element types serving the area are ofrather similar type, for instance a 2G-SGSN and a 3G-SGSN. In otherembodiments of the invention, the two types of core network elements mayhave different functionalities with respect to, for instance, user planerouting. It can be envisioned, for instance, that one type of thecorresponding network element types is only performing mobilitymanagement related functions, whereas the rest of the functions areperformed by other network elements. However, an another type of thecorresponding network element types would also perform additionally manyother functions such as participating in the routing of user planetraffic. However, they have at least one corresponding functionprovided, therefore they are only of corresponding types, not similarwith respect to the set of functions provided. By corresponding type ismeant that the two types of core network elements are both equippedwith, as already mentioned, at least the means of communicating with theaccess network.

Accordingly, as has been described herein before, the present inventionis a method of performing an area update for a terminal equipment 4A, 4Bin a communication network 1, 2, 3, 5, 6, the communication networkcomprising at least two areas 5, 6 being defined within an accessnetwork, at least one of said areas being served by at least two corenetwork elements 1-2, 2-3 of corresponding network element types, eachof said at least two core network elements communicating with saidaccess network defining said areas via a different interface Iu, Gb, themethod comprising the steps of: monitoring, at the terminal equipmentside, via which of said at least two core network elements 1, 2 servinga currently visited area 5 the communication with the terminal equipment4A is effected, detecting, at the terminal equipment side, an areaupdate condition for said terminal 4A, 4B, requesting, by said terminalequipment, an area update for said terminal equipment 4B, and whereinsaid terminal equipment 4B sets an identifier in said area updaterequest identifying the core network element via which the communicationwith the terminal equipment 4A has previously been effected. Stillfurther, the present invention proposes also an accordingly adaptedterminal equipment.

The core network element via which the communication with the terminalequipment 4A has previously been effected is identified with the aid ofthe type of access network interface between the access network and thecore network element.

Although the present invention has been described herein above withreference to its preferred embodiments, it should be understood thatnumerous modifications may be made thereto without departing from thespirit and scope of the invention. It is intended that all suchmodifications fall within the scope of the appended claims.

1. An apparatus, comprising a routing area change unit configured todetect a change of a first routing area to a second routing area andfurther configured to form a routing area update request to be sent intothe second routing area, the routing area update request comprising atleast a part of a routing area identifier of the first routing area,said routing area change unit further configured to selectively modifyat least a part of the routing area identifier of the routing areaupdate request so that the modified at least a part of the routing areaidentifier of the routing area update request identifies a type of corenetwork element with which the apparatus was in communication in thefirst routing area.
 2. The apparatus of claim 1, where the at least apart of the routing area identifier that can be selectively modifiedcomprises a routing area code.
 3. The apparatus of claim 1, where the atleast a part of the routing area identifier that can be selectivelymodified comprises a location area code.
 4. The apparatus of claim 1,where the at least a part of the routing area identifier that can beselectively modified consists of a most significant bit of a routingarea code.
 5. The apparatus of claim 1, where the at least a part of therouting area identifier that can be selectively modified consists of amost significant bit of a location area code.
 6. The apparatus of claim1, where the at least a part of the routing area identifier that can beselectively modified comprises at least one most significant bit of arouting area code.
 7. The apparatus of claim 1, where the at least apart of the routing area identifier that can be selectively modifiedcomprises at least one most significant bit of a location area code. 8.The apparatus of claim 1, where the core network element is comprised ofa serving general packet radio system support node that is interfaced tothe first routing area via a Gb interface.
 9. The apparatus of claim 1,where the core network element is comprised of a serving general packetradio system support node that is interfaced to the first routing areavia an Iu-PS interface.
 10. The apparatus of claim 1, wherein therouting area identifier comprises a mobile country code, a mobilenetwork code, a location area code, and a routing area code, and wherethe at least a part of the routing area identifier that is selectivelymodified comprises at least one bit of one of the routing area code orthe location area code.
 11. The apparatus of claim 1, where the firstrouting area is comprised of at least one cell served by at least onebase station, and further comprising a communication unit configured toconduct bidirectional radio frequency communication with the at leastone base station.
 12. The apparatus of claim 1, where the first routingarea is comprised of at least one cell served by at least one Node-B,and further comprising a communication unit configured to conductbidirectional radio frequency communication with the at least oneNode-B.
 13. The apparatus of claim 1, embodied in a communicationterminal.
 14. The apparatus of claim 1, embodied in a user equipment.15. A method, comprising: conducting bidirectional wirelesscommunication with an access network in a first routing area identifiedby a routing area identifier; and in response to detecting a change ofthe first routing area to a second routing area, sending a routing areaupdate request into the second routing area, the routing area updaterequest comprising at least a part of a routing area identifier of thefirst routing area, where sending comprises selectively modifying atleast a part of the routing area identifier of the first routing area sothat the modified at least a part of the routing area identifier of therouting area update request identifies a type of core network element inthe first routing area.
 16. The method of claim 15, where the at least apart of the routing area identifier that can be selectively modifiedcomprises a routing area code.
 17. The method of claim 15, where the atleast a part of the routing area identifier that can be selectivelymodified comprises a location area code.
 18. The method of claim 15,where the at least a part of the routing area identifier that can beselectively modified consists of a most significant bit of a routingarea code.
 19. The method of claim 15, where the at least a part of therouting area identifier that can be selectively modified consists of amost significant bit of a location area code.
 20. The method of claim15, where the at least a part of the routing area identifier that can beselectively modified comprises at least one most significant bit of arouting area code.
 21. The method of claim 15, where the at least a partof the routing area identifier that can be selectively modifiedcomprises at least one most significant bit of a location area code. 22.The method of claim 15, where the core network element is comprised of aserving general packet radio system support node that is interfaced tothe first routing area via a Gb interface.
 23. The method of claim 15,where the core network element is comprised of a serving general packetradio system support node that is interfaced to the first routing areavia an Iu-PS interface.
 24. The method of claim 15, wherein the routingarea identifier comprises a mobile country code, a mobile network code,a location area code, and a routing area code, and where the at least apart of the routing area identifier that can be selectively modifiedcomprises at least one bit of one of the routing area code or thelocation area code.
 25. The method of claim 15, where the first routingarea is comprised of at least one cell served by at least one basestation, and where conducting bidirectional wireless communicationconducts bidirectional radio frequency communication with the at leastone base station.
 26. The method of claim 15, where the first routingarea is comprised of at least one cell served by at least one Node-B,and where conducting bidirectional wireless communication conductsbidirectional radio frequency communication with the at least oneNode-B.
 27. The method of claim 15, performed in a communicationterminal.
 28. The method of claim 15, performed in a user equipment. 29.An apparatus, comprising a routing area unit configured to receive, viaan interface to an access network in a routing area, a routing areaupdate request originated by a mobile communication apparatus, therouting area update request comprising at least a part of a routing areaidentifier that can be selectively modified by the mobile communicationapparatus so that the modified at least a part of the routing areaidentifier of the routing area update request identifies a type of corenetwork element with which the mobile communication apparatus was incommunication in another routing area, said routing area unit furtherconfigured to exchange information with the identified type of corenetwork element to obtain information associated with the mobilecommunication apparatus.
 30. The apparatus of claim 29, where the atleast a part of the routing area identifier that can be selectivelymodified comprises a routing area code.
 31. The apparatus of claim 29,where the at least a part of the routing area identifier that can beselectively modified comprises a location area code.
 32. The apparatusof claim 29, where the at least a part of the routing area identifierthat can be selectively modified consists of a most significant bit of arouting area code.
 33. The apparatus of claim 29, where the at least apart of the routing area identifier that can be selectively modifiedconsists of a most significant bit of a location area code.
 34. Theapparatus of claim 29, where the at least a part of the routing areaidentifier that can be selectively modified comprises at least one mostsignificant bit of a routing area code.
 35. The apparatus of claim 29,where the at least a part of the routing area identifier that can beselectively modified comprises at least one most significant bit of alocation area code.
 36. The apparatus of claim 29, comprised of aserving general packet radio system support node that is interfaced tothe access network via a Gb interface.
 37. The apparatus of claim 29,comprised of a serving general packet radio system support node that isinterfaced to the access network via an Iu-PS interface.
 38. Theapparatus of claim 29, wherein the routing area identifier comprises amobile country code, a mobile network code, a location area code, and arouting area code, and where the at least a part of the routing areaidentifier that can be selectively modified comprises at least one bitof one of the routing area code or the location area code.
 39. Theapparatus of claim 29, where the access area is comprised of at leastone cell served by at least one base station.
 40. The apparatus of claim29, where the access area is comprised of at least one cell served by atleast one Node-B.
 41. A method, comprising: receiving, via an interfaceto an access network in a routing area, a routing area update requestoriginated by a mobile communication apparatus, the routing area updaterequest comprising at least a part of a routing area identifier that canbe selectively modified by the mobile communication apparatus so thatthe modified at least a part of the routing area identifier of therouting area update request identifies a type of core network elementwith which the mobile communication apparatus was in communication inanother routing area; and exchanging information with the identifiedtype of core network element to obtain information associated with themobile communication apparatus.
 42. The method of claim 41, where the atleast apart of the routing area identifier that can be selectivelymodified comprises a routing area code.
 43. The method of claim 41,where the at least a part of the routing area identifier that can beselectively modified comprises a location area code.
 44. The method ofclaim 41, where the at least a part of the routing area identifier thatcan be selectively modified consists of a most significant bit of arouting area code.
 45. The method of claim 41, where the at least a partof the routing area identifier that can be selectively modified consistsof a most significant bit of a location area code.
 46. The method ofclaim 41, where the at least a part of the routing area identifier thatcan be selectively modified comprises at least one most significant bitof a routing area code.
 47. The method of claim 41, where the at least apart of the routing area identifier that can be selectively modifiedcomprises at least one most significant bit of a location area code. 48.The method of claim 41, performed in a serving general packet radiosystem support node that is interfaced to the access network via a Gbinterface.
 49. The method of claim 41, performed in a serving generalpacket radio system support node that is interfaced to the accessnetwork via an Iu-PS interface.
 50. The method of claim 41, wherein therouting area identifier comprises a mobile country code, a mobilenetwork code, a location area code, and a routing area code, and wherethe at least a part of the routing area identifier that can beselectively modified comprises at least one bit of one of the routingarea code or the location area code.
 51. The method of claim 41, wherethe access area is comprised of at least one cell served by at least onebase station.
 52. The method of claim 41, where the access area iscomprised of at least one cell served by at least one Node-B.
 53. Anapparatus, comprising means for detecting a change of a first routingarea to a second routing area and means for composing a routing areaupdate request to be sent by a wireless communication into the secondrouting area, the routing area update request comprising at least a partof a routing area identifier of the first routing area that isselectively modifiable so that the modified at least a part of therouting area identifier of the routing area update request identifies atype of core network element with which the apparatus was incommunication in the first routing area.
 54. The apparatus of claim 53,where the at least a part of the routing area identifier that isselectively modifiable comprises a routing area code or a location areacode.
 55. An apparatus, comprising: means for receiving, via aninterface to an access network in a routing area, a routing area updaterequest originated by a mobile communication apparatus, the routing areaupdate request comprising at least a part of a routing area identifierthat can be selectively modified by the mobile communication apparatusso that the modified at least a part of the routing area identifier ofthe routing area update request identifies a type of core networkelement with which the mobile communication apparatus was incommunication in another routing area; and means for exchanginginformation with the identified type of core network element to obtaininformation associated with the mobile communication apparatus.
 56. Theapparatus of claim 55, where the at least a part of the routing areaidentifier that can be selectively modified comprises a routing areacode or a location area code.
 57. An apparatus, comprising routing areacircuitry configured to detect a change of a first routing area to asecond routing area and further configured to compose a routing areaupdate request to be sent by a wireless communication into the secondrouting area, the routing area update request comprising at least a partof a routing area identifier of the first routing area that isselectively modifiable so that the modified at least a part of therouting area identifier of the routing area update request identifies atype of core network element that serves the first routing area.
 58. Theapparatus of claim 57, where the at least a part of the routing areaidentifier that is selectively modifiable comprises a routing area codeor a location area code.
 59. The apparatus of claim 57, where the atleast a part of the routing area identifier that is selectivelymodifiable comprises at least one most significant bit of a routing areacode or a location area code.
 60. The apparatus of claim 57, where thecore network element is comprised of a serving general packet radiosystem support node that is interfaced to the first routing area via aGb interface or via an Iu-PS interface.